Intresting Ravenheat combi hot water problem

[tpw31]

I have a Ravenheat RSF 820/20 fanned combi.
Quite old.
Heating system works fine.
Hot water is recently inconsistent.
If I turn the heating off and just run the hot tap the boiler comes on and hot water, great. If I reduce the flow by turning the tap down the boiler will stop. Then if I turn the tap back on to full the boiler does not fire up, so I get cold water. If I shut the tap off completely and open it up again the boiler might fire up might not?

Strange. Any help appreciated.

 

[doitall]

82/20 could be the control thermostat or flow switch

 

[drgl]

Was a bloked venturi in the diverter valve when mine did that

 

[gastight]

Sound's as if the spindle in the diverter is not moving freely. May need lubricating with silicon grease.

The Diverter in the Raventheat is bu**er to take out. It is at back and expect the skin on the knuckles to be scraped, unless you have small hands.

 

[tpw31]

Ok can I do this by just turning the boiler off? Or would I need to drain the system?

 

[doitall]

Ok can I do this by just turning the boiler off? Or would I need to drain the system?

do what

you haven't decided whats wrong yet

 

[kevplumb]

tis obvious whats wrong tis broke

 

[tpw31]

Na i'll probably have to get a boiler man out to be sure

 

[kevplumb]

if you are going to play with the diverter valve you needto isolate the water supply and the boiler (taps under) and drain the boiler
or you are going to get wet

 

[doitall]

check he's familiar with your boiler when you phone.

 

[DP]

Kev, you did not say ' turn the power off as well'

Crap boiler, crap layout, all wires black (with numbers that never can be seen). Expect the electric to get wet. Can see this exercise turning to a disaster.

Went to one this morning. Sime boiler that was drained to do some radiator work. Plumber was in a panic last night as the boiler failed to start up at the end of the job. He had failed to purge the system causing the boiler to overheat and shut down.

 

[DP]

Wel done site admin. cr*p is automatically converted to rubbish. Woulk not mind such a program that converts a 'rubbish' day into sunshine and roses.

 

[PEDANTICVINDICTIVEMAN]

Be inventive with the spelling craap and buggger, bolllllocks ect tee hee

 

[tezteztez]

Hi all i'm new here I have a similar problem to this, I just want to check something before I buy the parts.
I've got the same ravenheat boiler had it in now for about 8 years has never let me down until now. When the heatings on the hot waters red hot, when it's off and I open the hot water tap it starts off red hot then starts to cool to a temp where you can keep your hand under it. If I feel the radiator flow pipe that comes from the back of the boiler it starts getting hot.
Am I correct in thinking that this is down to the diaphragm/diverter valve

Cheers Tez

 

[Slugbabydotcom]

Am I correct in thinking that this is down to the diaphragm/diverter valve

I would say so.

Here's a load of tips..... Have fun working on it!

Better to get a full valve in my opinion. Its too much hassle to risk just changing the diaphragm unless you have lots and lots of time to play with it.
They are as stated a pain to get work on unless you have the right tools.
Adjustable basin wrench with spring loaded head.[This is essential if you like the skin that covers your knuckles]
Waterpump pliers 8"
adjustable spanners.
As with all jobs like this be ever conscious of what will happen if you slip.
When you put the new one in put all 5 nuts on loose before tightening them.
Make sure you get a new set of sealing washers. These are usually supplied with a genuine manufacturers part.
I find that removing the pcb cover makes access a lot easier.
Theres a small plastic flow restrictor/filter on the mains water end of the valve. It always jumps out while you are fitting the valve. It will still work without it but obviously its there for a purpose and should be fitted.
The DV contains both Mains water and system water so make sure the supply is off, the boiler is isolated from the system and the remaining system water is drained from the boiler.